This application proposes a mediation-outcome research study evaluating the specificity, mediation, and treatment outcome enhancement of parent involvement for reducing anxiety disorders in children. The study targets the same DSM-IV anxiety disorders targeted in previous clinical trials and that are most common in children: social phobia, generalized anxiety disorder, and separation anxiety disorder. Using a controlled clinical trial design, 336 children (ages 8-11 years) and their parents will be admitted to treatment over the five years of the study, yielding an estimated 236 treatment completers at one year follow-up. Participants will be randomly assigned to one of the three treatment conditions. Two parent involvement conditions (1) ICBT+Parent Reinforcement Skills Training (ICBT+RFST) (i.e., increasing parental use of positive reinforcement and decreasing negative reinforcement) and (2) ICBT + Parent Relationship Skills Training (ICBT- RLST) (i.e., increasing parental autonomy granting and increasing parental child acceptance), and (3) a basic ICBT without additional parent involvement components as a baseline comparison condition. Children and parents will be assessed at pretreatment, midtreatment, posttreatment, and one-year follow up with questionnaire measures, the child and parent versions of the interview schedules, and observational measures. Three sets of hypotheses will be tested. The first set tests for specificity of effects, i.e., whether the addition of specific treatment components has the expected specific effects on the appropriately targeted parenting skills; the second set for mediation, i.e., whether the effects of changes in the hypothesized mediators are related to significant positive change in child treatment outcome. The third set tests for differential treatment outcome (i.e., whether positive change in child treatment outcome in the parent involvement conditions is significantly greater than positive change in child treatment outcome in the ICBT treatment condition, a baseline comparison condition).The multi-analytic strategies that will be used in the analysis of the data (including structural equation modeling and other complex data analytic strategies e.g., growth curve modeling) are described in detail under the Data Analysis Plan. This application proposes a mediation-outcome child anxiety treatment study that evaluates the specificity, mediation, and treatment outcome enhancement of two distinct strategies for involving parents in their child's treatment relative to individual treatment.